Heavy oil producers in Western Canada have generally accepted the notion that non-thermal heavy oil production is not economically feasible without allowing, and in some cases promoting, sand production. For instance, in the primary production of heavy oil, cold heavy oil production with sand (known as “CHOPS”) is currently one of the key production techniques utilized in the development of the heavy oil reserves or subterranean reservoirs. However, this operating strategy and method of production has led to operators producing as much as 500,000 m3 of sand per year. Handling and disposal cost for this by-product of oil production normally exceeds $100/m3. In addition, workovers on producing wells due to sand accumulation in the pumps and increased wear due to the presence of sand in the produced fluids routinely account for over 25% of heavy oil operating costs.
While the elimination of sand production may significantly reduce heavy oil operating costs, past experience has shown that the use of sand retention devices in primary production heavy oil wells may severely impair oil production rates. Therefore it appears that the sand must be produced.
Produced sand is currently handled as a waste product requiring special handling facilities, cleaning plants and some method of ultimate disposal. Many operators currently dispose of the produced sand in salt caverns. Some of these caverns were initially used for liquid and gaseous hydrocarbon storage while more recently some operators and service companies have constructed caverns expressly for produced sand disposal. The current production techniques, however, require the sand to be pumped to surface, trucked to a central facility, stockpiled and finally injected into the salt cavern. This process tends to be relatively expensive and increases the risk of environmental contamination due to increased transportation of sand over potentially long distances and prolonged surface storage.
The present methods of producing heavy oil rely on the use of individual well storage tanks for collecting produced fluids from either a single well or small groups of wells. These tanks are open to the atmosphere. While significant quantities of solution gas, principally methane, are produced, this gas is generally allowed to vent to atmosphere. For instance, it has been found that for each cubic meter of heavy oil produced there are typically 20 cubic meters of solution gas (primarily methane) vented to the atmosphere. Further, it has been suggested that the volume of gas vented from heavy oil wells in Western Canada may be in the order of 700 m3/day per well. Reducing this volume of vented “greenhouse gas” has become one of the more prominent mandates of the oil industry and the Province of Alberta, Canada as a whole.
Using flowlines or pipelines to collect heavy oil produced to the surface with sand, or sand-laden heavy oil, has been found to be both impractical and economically unattractive for various reasons, including concerns with the plugging of the flowlines by the sand. Thus, in most cases, heavy oil, sand and water are trucked to a central battery or facility, further contributing to greenhouse gas emissions and increasing road hazards to the general public. In addition, heavy oil wells often become unprofitable when the volume of water produced increases even when there is still significant daily oil production, due at least in part to the high cost of transporting the water from the well storage tanks to a disposal facility.
Thus, there remains a need for an improved system and method for the primary production of subterranean reservoirs, particularly those containing an oil component such as heavy oil. Preferably, the improved system and method address the production of a solid component, particularly sand, from the reservoir in a manner which may reduce the environmental impact and operating costs as compared with current primary production systems and methods.